SELF-SUPPORTING BUILDING SYSTEM

Abstract: Self-supporting construction system for comparatively large spans, basically consisting of a panel (1), e.g. an insulation panel, and one or more stiffening elements (2), such as an omega section, which in principle is mounted along the longitudinal axis of the panel (1). According to the invention at least one slender or comparatively thin section (8, 10, 11, 16) has been fitted to the joint between the panel (1) and the stiffening element (2), in such a way that the composite system can perform every mechanical function of the supporting structures a building requires.

Description: [Selfsupporting] building system. In most cases, a building in the (insulated) public utilities category consists of a supporting structure to which insulation covered panels are fitted. Often panels and insulation are combined into a supporting element in the shape of a sandwich panel. Because of the larger spans which are feasible with self¬ supporting panels, it is possible to save on the required quantity of trusses or portals. Due to the reduction in weight of the structure which may so be obtained and the subsequent reduction in the required construction time, it is possible to save on the cost of the supporting structure. In a few cases this concept has been carried even further, viz. the sandwich panels have been provided with a rigid supporting element, a stiffening element, as a result of which the span per panel may increase substantially whereas the cost price and the weight of the supporting structure will decrease. The reduction in weight of the supporting structure, however, is followed by an increase in the weight of the panels resulting from the addition of the stiffening element, and consequently the net savings in the construction costs do not fully reflect what is saved on the supporting structure. The invention involves a construction system which not only uses stiffened panels but in which the supporting structure is also combined with the panels. This yields self-supporting elements of a design which allows building without a separate supporting structure. Subsequently it also turns out to be possible to save on building material consumption as well as on building costs. Designs are possible in which the total weight of the superstructure for a hall with a free span of 20 m and a construction surface of 1000 m 2 will be approx. 25 kg/m 2 . It is obvious that major savings in building material consumption are involved here. Since both the production and the construction require little effort, few building facilities and few personnel, a quite sizeable reduction in costs of the total construction will be possible. Cost reductions in the order of 30-35% are feasible, as compared to the cheapest traditional construction methods. Based on the integration of panel and structure, a number of advantageous embodiments have been developed. Point of departure was a well-known stiffening method for (sandwich) panels, as illustrated in figures 1 and 2. This method consists of mounting an omega-shaped plate girder 2 under a sandwich panel 1. By filling this girder with a glued-in light core 3 the plate fields of this girder are stabilized, so that plate 2 can be very thin. In this manner an efficient in relation to weight, rigid roof element 5 is formed, with which large spans have been realized within the scope of the applicable building regulations. The construction of cladding units should be the same as that of the roof elements. A problem, however, is the absorption of vertical forces into the cladding units. The absorption of this load, also in accordance with applicable building regulations, requires such a ratio between plate thickness 2 and the plate field dimensions that economical application is no longer feasible, since plate 2 would become too thick. Designing the plate girders in such a way that they themselves are sufficiently stable would once again entail a quite sizeable increase in building material consumption. In principle, a few stiffening elements with an advantageous thickness/cross surface ratio will suffice to absorb the vertical load. In practice it turns out that these sections can be designed very light, provided they can be stabilized against buckling. Now the invention departs from the idea of using comparatively light or slender sections on flat shaped structural elements for the absorption of forces, predominantly directed along the longitudinal plane of the axis of symmetry of the structural element, while the elements themselves assist in stabilizing these sections against buckling or tilting. For that purpose, according to the invention, the self-supporting construction system, in which the system basically consists of a panel, e.g. an insulation panel, and one or more stiffening elements, such as an omega section, in principle mounted along the longitudinal axis of the panel, features at least one slender or comparatively thin section fitted to the joint between the panel and the stiffening element, in such a way that the composite system can perform every mechanical function of the supporting structures required for a building. The invention will be illustrated further by means of the figures, which will also demonstrate some advantageous embodiments. Figures 1 and 2 show a construction system which is the basis of the invention, and which has already been explained in the above introduction; Figure 3 shows the embodiment in which a slender section is mounted on the outside of the stiffening section; Figure 3a shows another embodiment for the stiffening element in figure 3; Figure 4 shows an outside wall/roof structure composed of the construction systems in accordance with the invention; Figure 5a shows another embodiment for a construction system; Figure 5b shows an embodiment in accordance with figure 5a, in which two panels were used; Figure 6 shows a frame of the construction system in accordance with figure 5a; Figure 7 shows another advantageous embodiment of the construction system; Figure 8 shows a special embodiment for two panels; Figure 9 shows an embodiment for a flat panel; Figures 10a-10c show various outside wall and roof structures using the construction system in accordance with the invention; Figure 11 shows an embodiment in accordance with the principle illustrated in figure 5, yet using a single-walled panel. According to figure 3 the comparatively thin or slender section 8 is fitted to the outside of stiffening element 2. Element 2, which as already known is a plate of the omega-shape or cap section, is fitted to (sandwich) panel 1. Construction parts 1, 2 and 8 are interconnected by means of pop rivets 9. One of the advantages of this embodiment is that section 8 is an angle section with an interior angle corresponding to the angle between panel 1 and stiffening section 2. As this is virtually a right angle, the section is stabilized in two planes, so that buckling is impossible. Executing section 8 as an L-section yields a restrained, elegant structure which can be produced easily. In that case, stabilization is provided by (shell) plates 2 of both (sandwich) panel 1 and the (omega) stiffening section, which are subsequently stabilized by their glued-in cores 3 (Figure 2). Figure 3a shows an advantageous embodiment of stiffening element 2, offering an especially safe structure with slender section 8 and construction parts 2a and 4. For that purpose a second element 2a is connected to panel 1 , around and at some distance of the first stiffening element 2. Interspace 4 contains a fireproof insulating core 4. A preferred embodiment is shown in figure 5a; this may be regarded as a slightly different implementation of the principle applied in the construction system in accordance with figures 3 and 3a. According to figure 5a, a panel 1 is stiffened and made into a supporting element also by utilizing slender sections 10, 11 and 12, which are stabilized against buckling by panel 1 itself. The difference with the embodiment according to figures 3 or 3a is that here plate stiffener 2 is not used, neither to stiffen panel 1 nor for the stabilization of the normal force absorbing slender sections. So the roof and/or wall element according to figure 5a is composed as follows: A panel 1 is provided with a slender section 10 which is placed on its upper layer 1a and which is secured in several spots. A second section 11 is arranged perpendicularly (in relation to cover surface 1a of section 1) above section 10, at some distance and parallel to it. Both sections 10 and 11 are interconnected by sections 12 which are fitted in a zigzag fashion. By bending ends 11a and 11b, see figure 6, of section 11 towards section 10 on cover layer 1a, junction A, an advantageous combination of a panel-frame girder is obtained. The forces occurring when this combination is bent manifest themselves mainly as internal forces in the frame structure. The loads on the connection between frames 10, 11, 12 and panel 1 will diminish because of the bending. It is obvious that when the structure bends, junctions A will have to transmit great forces from section 10 to section 11, as a result of the bending related relative changes in length between these sections. In fact here the force level is highest. The loads on sections 12, which are placed at an angle, are comparatively light, so that even lighter sections may be used here. For a standard commercial width of panel 1 and for spans up to approximately 30 m, e.g. the following sections may be used: Section 10: U-section 35/45/35*2 Section 11 : round tube 38*1.5 Section 12: round tube 27*1.5 These comparatively thin sections are excellently capable of absorbing the forces without the permissible material stresses being exceeded. However, in order to prevent such a frame, already provided with insulation material, from being unable to supply the required bearing capacity and stiffness, when the stability limit is exceeded far before the permissible stresses are reached, due to buckling of the sections, steps are taken to obtain the required stability viz. by connecting members 13 from outermost section 11 to panel 1. The characteristic feature of the preferred embodiment is that members 13 are in a plane perpendicular to the frame formed by sections 10-12. With respect to the stabilization of the embodiment according to figure 5a (and figure 5b), one further remark should be made: by being secured to the cover surface of panel 1 , U-section 10 is stabilized in this plane by the cover surface itself. Perpendicular to this plane, stabilization is provided partly by (sandwich) panel 1 and partly by the slanting sections or members 12. By so fitting a sufficiently large number of slanting sections 12 and connections or members 13 to the cover surface of panel 1, sufficient stability for the required function can be obtained in two planes perpendicular to one another. Tubular section 11 obtains stability, in the direction perpendicular to the cover surface, through slanting sections 12. Since these sections are connected with panel 1, either directly or by means of section 10, the final stability in this direction is provided by panel 1. In the direction parallel to the cover surface the stability for section 11 may not be quite sufficient to warrant using the structure as such. By also placing members 13 at an angle, from section 11 to panel 1 and outside the plane of frame 12, section 11 is supported against the panel. The support component parallel to the cover surface provides stability in this direction. As for the slender section construction, the embodiment according to figure 5b is equal to that according to figure 5a; the advantage, however, is that the round section 11 has been replaced by U-section 10, to which a panel 1 is fitted. It turns out that this has a favourable effect on the bearing capacity of the frame thus obtained; said bearing capacity has increased by a factor 6-8. Finally, by stabilizing section 11 (section 10 in figure 5a) the frame has also been stabilized sufficiently since sections/members 12 and 13 are sufficiently short in length to absorb the loads without buckling, without requiring any additional facilities. An advantageous version of the construction system design according to figure 5a is shown in figure 7. The characteristic feature of this version is that one or more panels 1 have been fitted with slender sections 8, which are connected to only one slender section 11 , located at a distance, by means of members 14 which are placed at an angle, zigzag fashion. In this case the functions of sections/ members 12 and 13 have been incorporated into one member. In the embodiment shown two panels 1 are interconnected sideways by appropriate means 15. Both panels are provided with a slender section 8 and now only one (round) section 11 is placed parallel to the sections 8 above the panels. Subsequently the sections 8 are connected with section 11 by members 14, placed at an angle in a zigzag pattern. Furthermore it is important that the two panels are properly interconnected, so that they will not come apart as a result of the lateral thrusts occurring in case of bending. For that purpose provisions may be made by way of coupling elements 15 between sections 1. By placing these coupling elements 15 in a zigzag pattern as well, the entire structure will gain in torsional stiffness, so that very large spans can be realized without additional elements being required to interconnect the hall segments. This may be important e.g. in the construction of hangars for large aeroplanes, as the design of the structure can be lighter. If panels with suitable dimensions are used, it is also possible to provide only one panel with two sections 8 and fix members 14 to this in a zigzag pattern. In this embodiment the occurring lateral thrusts are mainly absorbed by the cover layer of panel 1. Another advantageous embodiment according to the invention is shown in figure 8. It involves a panel 1 which has been turned at an appropriate angle α. The sides of this panel have also been provided with comparatively slender sections 16 which are interconnectable, in such a way that this system too meets the requirement for safe composition of zigzag shaped walls and/or roofs. The extent to which the panels 1 will stabilize the sections 16 against buckling mainly depends on the angle α at which the panel 1 has been set. Based on a certain load and longitudinal dimension of the panel 1, this angle will also determine the minimal slenderness of the sections 16 fitted to the sides. This slendemess is important, since a slender section will cause less of an interruption in the panel material (insulation) than a thicker section, when section 16 is placed inside the cover layers 1a of panel 1. In marginal cases this section 16 will diminish into a solid member or strip, which from an economical point of view offers the best solution. By providing panels 1a, in accordance with the system shown in figure 8, with the usual male-female couplings 16, adapted to angle α between panels 1 , these panels may so be made up into walls and roofs as well. In principle, the sections located near these couplings may be used to accommodate the fixing elements with which panels 1a can be interconnected. Figure 9 shows another advantageous embodiment, in which now a side 17 of (flat) panel 1b has been turned at an angle β, while the opposite side has been provided with the slender section 16. As already stated before, the extent to which the sections are stabilized against buckling will depend on the angles or β at which the panels 1a or 1b are interconnected. By executing the embodiment according to figure 9, the optimum height of the frame is now obtained as well. In order to construct entire buildings with panels 1a or 1b according to the system shown in figures 8 or 9, the ends of several of the composing panels need to be chamfered in the well-known fashion, by cutting or sawing, since otherwise the wall and roof elements cannot be connected without chinks (insulation requirement). An application of a construction system as shown e.g. in figure 5a is demonstrated in figures 10a-10c. The construction systems erected and interconnected form a segment of a hall. For a flat-roofed hall, figure 10b, the minimum is three construction systems; a saddle-roofed hall, figure 10a, requires a minimum of four construction systems. This embodiment also uses parts 17, which serve as tie-bars to interconnect sections 11 of the systems. By fitting laterally placed angle sections 18 and strips 19, moment transmitting couplings are obtained when parts 18 and 19 are connected both to the two adjoining (sandwich) panels 1 and to the two adjoining sections 10. Such a hall segment with a span of approximately 20 mm and a panel width of 1.15 m has a stiffness per hall segment corresponding to that of an IPE 270 section, which amounts to an equivalent hall structure of one portal frame timber made of IPE 270 sections per 1.15 m. It will now be clear that with all applications of the construction system according to the invention a building (walls, saddle-roofs, corrugated roofs etc.) is obtained which consumes considerably less building material; a factor that is of major economic significance, considering the extent of the building sector. Finally it is stated that the panel 1 as indicated above is a construction element in the broadest sense, and thus is not limited to sandwich panels. Therefore advantages may be gained by using panels whose composition entails certain qualities, e.g. panels which are equipped with light-transmitting components. Likewise it is also possible, in accordance with figure 11, to use a single-walled panel or a flat or corrugated plate 21 instead of a sandwich or composite panel. The advantage of this embodiment is that the building costs can be reduced even further. Favourable in this respect is that plate 21 is connected to a slender section 23, which is also connected to members 12, mounted zigzag fashion, and which by means of cross members 22 and members 13 is linked with the outermost section of purlin 11. This construction provides sufficient stabilization for the building element, in all directions. It should be noted that when a flat (single) plate is used, cross members 22 together with (stabilization) members 13 have sufficient moment transmitting capability.

Claims: Claims 1. Self-supporting construction system, in which the system is basically composed of a panel, e.g. an insulation panel, and one or more stiffening elements, such as an omega section, which in principle is fitted along the longitudinal axis of the panel, characterized in that at least one slender or comparatively thin section (8, 10, 11 , 16) is fitted to the connection between the panel (1) and the stiffening element (2), this in such a way that the composite system can perform all mechanical functions of the supporting structures required for a building. 2. Construction system in accordance with claim 1 , with characterized in that a slender section (8) is mounted on the outside of stiffening section (2). 3. Construction system in accordance with claims 1 or 2, characterized in that the slender section (8) is an angle section with an interior angle corresponding to the angle between the panel (1) and the stiffening section (2). 4. Construction system in accordance with one of the claims above, characterized in that a second stiffening section (2a) has been fitted at some distance around the first section (2), while a fireproof insulating core (4) has been introduced in the space between the two sections. 5. Construction system in accordance with claim 1 , characterized in that a slender section (10) has been mounted on the panel (1) with a second section (11) perpendicularly above the first; the two sections (10, 11) are interconnected by members/sections (12) fitted zigzag fashion. 6. Construction system in accordance with claim 5, characterized in that a panel 1 has also been fitted to the second section. 7. Construction system in accordance with claims 5 or 6, characterized in that the ends (11a, 11 b) of the outermost section (11) are bent towards and connected to the section (10) mounted on the panel (1). 8. Construction system in accordance with one of the claims 5-6 above, characterized in that members (13) run at an angle from the upper or outermost section (11) to the panel (1), with which they are connected or by which they are supported. 9. Construction system in accordance with claim 8, characterized in that the members (13) are in a plane perpendicular to the frame formed by the sections (10-12). 10. Construction system in accordance with claim 5 and one or more of the claims above, characterized in that a slender section (23) is connected with a single plate or single-walled panel (21). 11. Construction system in accordance with claim 10, characterized in that the members (13) at the ends pointing away from the outermost section or purlin (11) are connected with a cross member (22). 12. Construction system in accordance with claims 10 and 11 , characterized in that the slender section (23) is also connected with the members mounted zigzag fashion (12) and the cross-members (22). 13. Construction system in accordance with claim 1 and one or more of the claims above, characterized in that on one or more panels (1) sections (8) have been mounted that are connected to only one second section (11), located at a distance, by means of members (14) placed at an angle and zigzag fashion. 14. Construction system in accordance with one of the claims above, characterized in that a panel (1) has been turned over at an angle α into at least two panels (1a) of which the sides have been provided with comparatively slender sections (16) as well, which are interconnectable in such a way that this system meets the requirements for the formation of zigzag shaped walls and/or roofs. 15. Construction system in accordance with one of the claims above, characterized in that one of the sides (17) of a flat panel (1 b) has been turned over at an angle β and can be connected to another (flat) panel. 16. Building, characterized in that the roofs and/or outside walls are composed of construction systems in accordance with one or more of the foregoing claims.

Inventors: HOUWER GERKE, HOUWER, GERKE
Applicants: HOUWER GERKE, HOUWER, GERKE
Application year: 1994
Main classification: E04B5
IPC codes: E04B5, E04B7, E04C3